[v4,2/2] Adding i2c-cp2615: i2c support for Silicon Labs' CP2615 Digital Audio Bridge

Message ID 20210331191921.1066172-3-bence98@sch.bme.hu
State New
Headers show
Series
  • Untitled series #116191
Related show

Commit Message

Bence Csókás March 31, 2021, 7:19 p.m.
Create an i2c_adapter for CP2615's I2C master interface

Signed-off-by: Bence Csókás <bence98@sch.bme.hu>
---
 MAINTAINERS                     |   5 +
 drivers/i2c/busses/Kconfig      |  10 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-cp2615.c | 336 ++++++++++++++++++++++++++++++++
 4 files changed, 352 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-cp2615.c

Comments

kernel test robot March 31, 2021, 8:46 p.m. | #1
Hi "Bence,

I love your patch! Yet something to improve:

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on linux/master linus/master v5.12-rc5 next-20210331]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Bence-Cs-k-s/Adding-i2c-cp2615-i2c-support-for-Silicon-Labs-CP2615-Digital-Audio/20210401-030413
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
config: sh-allmodconfig (attached as .config)
compiler: sh4-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/f7bd7e90cde56628778fb121154088af095d3fa8
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Bence-Cs-k-s/Adding-i2c-cp2615-i2c-support-for-Silicon-Labs-CP2615-Digital-Audio/20210401-030413
        git checkout f7bd7e90cde56628778fb121154088af095d3fa8
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=sh 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   drivers/i2c/busses/i2c-cp2615.c:323:1: warning: data definition has no type or storage class
     323 | MODULE_DEVICE_TABLE(usb, id_table);
         | ^~~~~~~~~~~~~~~~~~~
>> drivers/i2c/busses/i2c-cp2615.c:323:1: error: type defaults to 'int' in declaration of 'MODULE_DEVICE_TABLE' [-Werror=implicit-int]
   drivers/i2c/busses/i2c-cp2615.c:323:1: warning: parameter names (without types) in function declaration
   In file included from include/linux/device.h:32,
                    from include/linux/acpi.h:15,
                    from include/linux/i2c.h:13,
                    from drivers/i2c/busses/i2c-cp2615.c:9:
   include/linux/device/driver.h:263:1: warning: data definition has no type or storage class
     263 | module_init(__driver##_init); \
         | ^~~~~~~~~~~
   include/linux/usb.h:1305:2: note: in expansion of macro 'module_driver'
    1305 |  module_driver(__usb_driver, usb_register, \
         |  ^~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: note: in expansion of macro 'module_usb_driver'
     332 | module_usb_driver(cp2615_i2c_driver);
         | ^~~~~~~~~~~~~~~~~
>> include/linux/device/driver.h:263:1: error: type defaults to 'int' in declaration of 'module_init' [-Werror=implicit-int]
     263 | module_init(__driver##_init); \
         | ^~~~~~~~~~~
   include/linux/usb.h:1305:2: note: in expansion of macro 'module_driver'
    1305 |  module_driver(__usb_driver, usb_register, \
         |  ^~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: note: in expansion of macro 'module_usb_driver'
     332 | module_usb_driver(cp2615_i2c_driver);
         | ^~~~~~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: warning: parameter names (without types) in function declaration
   In file included from include/linux/device.h:32,
                    from include/linux/acpi.h:15,
                    from include/linux/i2c.h:13,
                    from drivers/i2c/busses/i2c-cp2615.c:9:
   include/linux/device/driver.h:268:1: warning: data definition has no type or storage class
     268 | module_exit(__driver##_exit);
         | ^~~~~~~~~~~
   include/linux/usb.h:1305:2: note: in expansion of macro 'module_driver'
    1305 |  module_driver(__usb_driver, usb_register, \
         |  ^~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: note: in expansion of macro 'module_usb_driver'
     332 | module_usb_driver(cp2615_i2c_driver);
         | ^~~~~~~~~~~~~~~~~
>> include/linux/device/driver.h:268:1: error: type defaults to 'int' in declaration of 'module_exit' [-Werror=implicit-int]
     268 | module_exit(__driver##_exit);
         | ^~~~~~~~~~~
   include/linux/usb.h:1305:2: note: in expansion of macro 'module_driver'
    1305 |  module_driver(__usb_driver, usb_register, \
         |  ^~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: note: in expansion of macro 'module_usb_driver'
     332 | module_usb_driver(cp2615_i2c_driver);
         | ^~~~~~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: warning: parameter names (without types) in function declaration
>> drivers/i2c/busses/i2c-cp2615.c:334:15: error: expected declaration specifiers or '...' before string constant
     334 | MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
         |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:335:20: error: expected declaration specifiers or '...' before string constant
     335 | MODULE_DESCRIPTION("CP2615 I2C bus driver");
         |                    ^~~~~~~~~~~~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:336:16: error: expected declaration specifiers or '...' before string constant
     336 | MODULE_LICENSE("GPL");
         |                ^~~~~
   In file included from include/linux/device.h:32,
                    from include/linux/acpi.h:15,
                    from include/linux/i2c.h:13,
                    from drivers/i2c/busses/i2c-cp2615.c:9:
   drivers/i2c/busses/i2c-cp2615.c:332:19: warning: 'cp2615_i2c_driver_exit' defined but not used [-Wunused-function]
     332 | module_usb_driver(cp2615_i2c_driver);
         |                   ^~~~~~~~~~~~~~~~~
   include/linux/device/driver.h:264:20: note: in definition of macro 'module_driver'
     264 | static void __exit __driver##_exit(void) \
         |                    ^~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: note: in expansion of macro 'module_usb_driver'
     332 | module_usb_driver(cp2615_i2c_driver);
         | ^~~~~~~~~~~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:19: warning: 'cp2615_i2c_driver_init' defined but not used [-Wunused-function]
     332 | module_usb_driver(cp2615_i2c_driver);
         |                   ^~~~~~~~~~~~~~~~~
   include/linux/device/driver.h:259:19: note: in definition of macro 'module_driver'
     259 | static int __init __driver##_init(void) \
         |                   ^~~~~~~~
   drivers/i2c/busses/i2c-cp2615.c:332:1: note: in expansion of macro 'module_usb_driver'
     332 | module_usb_driver(cp2615_i2c_driver);
         | ^~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for SND_ATMEL_SOC_PDC
   Depends on SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC && HAS_DMA
   Selected by
   - SND_ATMEL_SOC_SSC && SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC
   - SND_ATMEL_SOC_SSC_PDC && SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC && ATMEL_SSC


vim +323 drivers/i2c/busses/i2c-cp2615.c

   322	
 > 323	MODULE_DEVICE_TABLE(usb, id_table);
   324	
   325	static struct usb_driver cp2615_i2c_driver = {
   326		.name = "i2c-cp2615",
   327		.probe = cp2615_i2c_probe,
   328		.disconnect = cp2615_i2c_remove,
   329		.id_table = id_table,
   330	};
   331	
   332	module_usb_driver(cp2615_i2c_driver);
   333	
 > 334	MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot April 1, 2021, 6:11 a.m. | #2
Hi "Bence,

I love your patch! Yet something to improve:

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on linux/master linus/master v5.12-rc5 next-20210331]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Bence-Cs-k-s/Adding-i2c-cp2615-i2c-support-for-Silicon-Labs-CP2615-Digital-Audio/20210401-030413
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
config: riscv-randconfig-r032-20210401 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 1c268a8ff4e90a85d0e634350b1104080614cf2b)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # https://github.com/0day-ci/linux/commit/f7bd7e90cde56628778fb121154088af095d3fa8
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Bence-Cs-k-s/Adding-i2c-cp2615-i2c-support-for-Silicon-Labs-CP2615-Digital-Audio/20210401-030413
        git checkout f7bd7e90cde56628778fb121154088af095d3fa8
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=riscv 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All error/warnings (new ones prefixed by >>):

>> drivers/i2c/busses/i2c-cp2615.c:323:1: warning: declaration specifier missing, defaulting to 'int'

   MODULE_DEVICE_TABLE(usb, id_table);
   ^
   int
>> drivers/i2c/busses/i2c-cp2615.c:323:21: error: a parameter list without types is only allowed in a function definition

   MODULE_DEVICE_TABLE(usb, id_table);
                       ^
   drivers/i2c/busses/i2c-cp2615.c:332:1: warning: declaration specifier missing, defaulting to 'int'
   module_usb_driver(cp2615_i2c_driver);
   ^
   include/linux/usb.h:1305:2: note: expanded from macro 'module_usb_driver'
           module_driver(__usb_driver, usb_register, \
           ^
   include/linux/device/driver.h:262:3: note: expanded from macro 'module_driver'
   } \
     ^
   drivers/i2c/busses/i2c-cp2615.c:332:1: error: a parameter list without types is only allowed in a function definition
   include/linux/usb.h:1305:2: note: expanded from macro 'module_usb_driver'
           module_driver(__usb_driver, usb_register, \
           ^
   include/linux/device/driver.h:263:13: note: expanded from macro 'module_driver'
   module_init(__driver##_init); \
               ^
   <scratch space>:203:1: note: expanded from here
   cp2615_i2c_driver_init
   ^
   drivers/i2c/busses/i2c-cp2615.c:332:1: warning: declaration specifier missing, defaulting to 'int'
   include/linux/usb.h:1305:2: note: expanded from macro 'module_usb_driver'
           module_driver(__usb_driver, usb_register, \
           ^
   include/linux/device/driver.h:267:3: note: expanded from macro 'module_driver'
   } \
     ^
   drivers/i2c/busses/i2c-cp2615.c:332:1: error: a parameter list without types is only allowed in a function definition
   include/linux/usb.h:1305:2: note: expanded from macro 'module_usb_driver'
           module_driver(__usb_driver, usb_register, \
           ^
   include/linux/device/driver.h:268:13: note: expanded from macro 'module_driver'
   module_exit(__driver##_exit);
               ^
   <scratch space>:205:1: note: expanded from here
   cp2615_i2c_driver_exit
   ^
>> drivers/i2c/busses/i2c-cp2615.c:334:15: error: expected parameter declarator

   MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
                 ^
>> drivers/i2c/busses/i2c-cp2615.c:334:15: error: expected ')'

   drivers/i2c/busses/i2c-cp2615.c:334:14: note: to match this '('
   MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
                ^
   drivers/i2c/busses/i2c-cp2615.c:334:1: warning: declaration specifier missing, defaulting to 'int'
   MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
   ^
   int
>> drivers/i2c/busses/i2c-cp2615.c:334:14: error: this function declaration is not a prototype [-Werror,-Wstrict-prototypes]

   MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
                ^
                                                    void
   drivers/i2c/busses/i2c-cp2615.c:335:20: error: expected parameter declarator
   MODULE_DESCRIPTION("CP2615 I2C bus driver");
                      ^
   drivers/i2c/busses/i2c-cp2615.c:335:20: error: expected ')'
   drivers/i2c/busses/i2c-cp2615.c:335:19: note: to match this '('
   MODULE_DESCRIPTION("CP2615 I2C bus driver");
                     ^
   drivers/i2c/busses/i2c-cp2615.c:335:1: warning: declaration specifier missing, defaulting to 'int'
   MODULE_DESCRIPTION("CP2615 I2C bus driver");
   ^
   int
   drivers/i2c/busses/i2c-cp2615.c:335:19: error: this function declaration is not a prototype [-Werror,-Wstrict-prototypes]
   MODULE_DESCRIPTION("CP2615 I2C bus driver");
                     ^
                                             void
   drivers/i2c/busses/i2c-cp2615.c:336:16: error: expected parameter declarator
   MODULE_LICENSE("GPL");
                  ^
   drivers/i2c/busses/i2c-cp2615.c:336:16: error: expected ')'
   drivers/i2c/busses/i2c-cp2615.c:336:15: note: to match this '('
   MODULE_LICENSE("GPL");
                 ^
   drivers/i2c/busses/i2c-cp2615.c:336:1: warning: declaration specifier missing, defaulting to 'int'
   MODULE_LICENSE("GPL");
   ^
   int
   drivers/i2c/busses/i2c-cp2615.c:336:15: error: this function declaration is not a prototype [-Werror,-Wstrict-prototypes]
   MODULE_LICENSE("GPL");
                 ^
                       void
   6 warnings and 12 errors generated.


vim +323 drivers/i2c/busses/i2c-cp2615.c

   322	
 > 323	MODULE_DEVICE_TABLE(usb, id_table);

   324	
   325	static struct usb_driver cp2615_i2c_driver = {
   326		.name = "i2c-cp2615",
   327		.probe = cp2615_i2c_probe,
   328		.disconnect = cp2615_i2c_remove,
   329		.id_table = id_table,
   330	};
   331	
   332	module_usb_driver(cp2615_i2c_driver);
   333	
 > 334	MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");


---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Wolfram Sang April 5, 2021, 8:46 p.m. | #3
On Wed, Mar 31, 2021 at 07:19:21PM +0000, Bence Csókás wrote:
> Create an i2c_adapter for CP2615's I2C master interface

> 

> Signed-off-by: Bence Csókás <bence98@sch.bme.hu>


Switched to '__packed', add some more 'static', added <module.h>, and
applied to for-next, thanks!

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 281de213ef47..d7ca6ad75d87 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4521,6 +4521,11 @@  F:	drivers/counter/
 F:	include/linux/counter.h
 F:	include/linux/counter_enum.h
 
+CP2615 I2C DRIVER
+M:	Bence Csókás <bence98@sch.bme.hu>
+S:	Maintained
+F:	drivers/i2c/busses/i2c-cp2615.c
+
 CPMAC ETHERNET DRIVER
 M:	Florian Fainelli <f.fainelli@gmail.com>
 L:	netdev@vger.kernel.org
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index a49e0ed4a599..7a0dd18140d3 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1227,6 +1227,16 @@  config I2C_DLN2
 	 This driver can also be built as a module.  If so, the module
 	 will be called i2c-dln2.
 
+config I2C_CP2615
+	tristate "Silicon Labs CP2615 USB sound card and I2C adapter"
+	depends on USB
+	help
+	  If you say yes to this option, support will be included for Silicon
+	  Labs CP2615's I2C interface.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-cp2615.
+
 config I2C_PARPORT
 	tristate "Parallel port adapter"
 	depends on PARPORT
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 683c49faca05..adb71d9c9d42 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -127,6 +127,7 @@  obj-$(CONFIG_I2C_ZX2967)	+= i2c-zx2967.o
 # External I2C/SMBus adapter drivers
 obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o
 obj-$(CONFIG_I2C_DLN2)		+= i2c-dln2.o
+obj-$(CONFIG_I2C_CP2615) += i2c-cp2615.o
 obj-$(CONFIG_I2C_PARPORT)	+= i2c-parport.o
 obj-$(CONFIG_I2C_ROBOTFUZZ_OSIF)	+= i2c-robotfuzz-osif.o
 obj-$(CONFIG_I2C_TAOS_EVM)	+= i2c-taos-evm.o
diff --git a/drivers/i2c/busses/i2c-cp2615.c b/drivers/i2c/busses/i2c-cp2615.c
new file mode 100644
index 000000000000..cd4146f7e60b
--- /dev/null
+++ b/drivers/i2c/busses/i2c-cp2615.c
@@ -0,0 +1,336 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * i2c support for Silicon Labs' CP2615 Digital Audio Bridge
+ *
+ * (c) 2021, Bence Csókás <bence98@sch.bme.hu>
+ */
+
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/usb.h>
+
+/** CP2615 I/O Protocol implementation */
+
+#define CP2615_VID 0x10c4
+#define CP2615_PID 0xeac1
+
+#define IOP_EP_IN  0x82
+#define IOP_EP_OUT 0x02
+#define IOP_IFN 1
+#define IOP_ALTSETTING 2
+
+#define MAX_IOP_SIZE 64
+#define MAX_IOP_PAYLOAD_SIZE (MAX_IOP_SIZE - 6)
+#define MAX_I2C_SIZE (MAX_IOP_PAYLOAD_SIZE - 4)
+
+enum cp2615_iop_msg_type {
+	iop_GetAccessoryInfo = 0xD100,
+	iop_AccessoryInfo = 0xA100,
+	iop_GetPortConfiguration = 0xD203,
+	iop_PortConfiguration = 0xA203,
+	iop_DoI2cTransfer = 0xD400,
+	iop_I2cTransferResult = 0xA400,
+	iop_GetSerialState = 0xD501,
+	iop_SerialState = 0xA501
+};
+
+struct __attribute__((packed)) cp2615_iop_msg {
+	__be16 preamble, length, msg;
+	u8 data[MAX_IOP_PAYLOAD_SIZE];
+};
+
+int cp2615_init_iop_msg(struct cp2615_iop_msg *ret, enum cp2615_iop_msg_type msg,
+			const void *data, size_t data_len);
+
+#define PART_ID_A01 0x1400
+#define PART_ID_A02 0x1500
+
+struct __attribute__((packed)) cp2615_iop_accessory_info {
+	__be16 part_id, option_id, proto_ver;
+};
+
+struct __attribute__((packed)) cp2615_i2c_transfer {
+	u8 tag, i2caddr, read_len, write_len;
+	u8 data[MAX_I2C_SIZE];
+};
+
+/* Possible values for struct cp2615_i2c_transfer_result.status */
+enum cp2615_i2c_status {
+	/* Writing to the internal EEPROM failed, because it is locked */
+	CP2615_CFG_LOCKED = -6,
+	/* read_len or write_len out of range */
+	CP2615_INVALID_PARAM = -4,
+	/* I2C slave did not ACK in time */
+	CP2615_TIMEOUT,
+	/* I2C bus busy */
+	CP2615_BUS_BUSY,
+	/* I2C bus error (ie. device NAK'd the request) */
+	CP2615_BUS_ERROR,
+	CP2615_SUCCESS
+};
+
+struct __attribute__((packed)) cp2615_i2c_transfer_result {
+	u8 tag, i2caddr;
+	s8 status;
+	u8 read_len;
+	u8 data[MAX_I2C_SIZE];
+};
+
+int cp2615_init_i2c_msg(struct cp2615_iop_msg *ret, const struct cp2615_i2c_transfer *data);
+
+/* Translates status codes to Linux errno's */
+int cp2615_check_status(enum cp2615_i2c_status status);
+
+int cp2615_init_iop_msg(struct cp2615_iop_msg *ret, enum cp2615_iop_msg_type msg,
+			const void *data, size_t data_len)
+{
+	if (data_len > MAX_IOP_PAYLOAD_SIZE)
+		return -EFBIG;
+
+	if (!ret)
+		return -EINVAL;
+
+	ret->preamble = 0x2A2A;
+	ret->length = htons(data_len + 6);
+	ret->msg = htons(msg);
+	if (data && data_len)
+		memcpy(&ret->data, data, data_len);
+	return 0;
+}
+
+int cp2615_init_i2c_msg(struct cp2615_iop_msg *ret, const struct cp2615_i2c_transfer *data)
+{
+	return cp2615_init_iop_msg(ret, iop_DoI2cTransfer, data, 4 + data->write_len);
+}
+
+int cp2615_check_status(enum cp2615_i2c_status status)
+{
+	switch (status) {
+	case CP2615_SUCCESS:
+			return 0;
+	case CP2615_BUS_ERROR:
+		return -ENXIO;
+	case CP2615_BUS_BUSY:
+		return -EAGAIN;
+	case CP2615_TIMEOUT:
+		return -ETIMEDOUT;
+	case CP2615_INVALID_PARAM:
+		return -EINVAL;
+	case CP2615_CFG_LOCKED:
+		return -EPERM;
+	}
+	/* Unknown error code */
+	return -EPROTO;
+}
+
+/** Driver code */
+
+static int
+cp2615_i2c_send(struct usb_interface *usbif, struct cp2615_i2c_transfer *i2c_w)
+{
+	struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	int res = cp2615_init_i2c_msg(msg, i2c_w);
+
+	if (!res)
+		res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
+				   msg, ntohs(msg->length), NULL, 0);
+	kfree(msg);
+	return res;
+}
+
+static int
+cp2615_i2c_recv(struct usb_interface *usbif, unsigned char tag, void *buf)
+{
+	struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
+	struct cp2615_i2c_transfer_result *i2c_r = (struct cp2615_i2c_transfer_result *)&msg->data;
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	int res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),
+			       msg, sizeof(struct cp2615_iop_msg), NULL, 0);
+
+	if (res < 0) {
+		kfree(msg);
+		return res;
+	}
+
+	if (msg->msg != htons(iop_I2cTransferResult) || i2c_r->tag != tag) {
+		kfree(msg);
+		return -EIO;
+	}
+
+	res = cp2615_check_status(i2c_r->status);
+	if (!res)
+		memcpy(buf, &i2c_r->data, i2c_r->read_len);
+
+	kfree(msg);
+	return res;
+}
+
+/* Checks if the IOP is functional by querying the part's ID */
+static int cp2615_check_iop(struct usb_interface *usbif)
+{
+	struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
+	struct cp2615_iop_accessory_info *info = (struct cp2615_iop_accessory_info *)&msg->data;
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	int res = cp2615_init_iop_msg(msg, iop_GetAccessoryInfo, NULL, 0);
+
+	if (res)
+		goto out;
+
+	res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
+				   msg, ntohs(msg->length), NULL, 0);
+	if (res)
+		goto out;
+
+	res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),
+			       msg, sizeof(struct cp2615_iop_msg), NULL, 0);
+	if (res)
+		goto out;
+
+	if (msg->msg != htons(iop_AccessoryInfo)) {
+		res = -EIO;
+		goto out;
+	}
+
+	switch (ntohs(info->part_id)) {
+	case PART_ID_A01:
+		dev_dbg(&usbif->dev, "Found A01 part. (WARNING: errata exist!)\n");
+		break;
+	case PART_ID_A02:
+		dev_dbg(&usbif->dev, "Found good A02 part.\n");
+		break;
+	default:
+		dev_warn(&usbif->dev, "Unknown part ID %04X\n", ntohs(info->part_id));
+	}
+
+out:
+	kfree(msg);
+	return res;
+}
+
+static int
+cp2615_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct usb_interface *usbif = adap->algo_data;
+	int i = 0, ret = 0;
+	struct i2c_msg *msg;
+	struct cp2615_i2c_transfer i2c_w = {0};
+
+	dev_dbg(&usbif->dev, "Doing %d I2C transactions\n", num);
+
+	for (; !ret && i < num; i++) {
+		msg = &msgs[i];
+
+		i2c_w.tag = 0xdd;
+		i2c_w.i2caddr = i2c_8bit_addr_from_msg(msg);
+		if (msg->flags & I2C_M_RD) {
+			i2c_w.read_len = msg->len;
+			i2c_w.write_len = 0;
+		} else {
+			i2c_w.read_len = 0;
+			i2c_w.write_len = msg->len;
+			memcpy(&i2c_w.data, msg->buf, i2c_w.write_len);
+		}
+		ret = cp2615_i2c_send(usbif, &i2c_w);
+		if (ret)
+			break;
+		ret = cp2615_i2c_recv(usbif, i2c_w.tag, msg->buf);
+	}
+	if (ret < 0)
+		return ret;
+	return i;
+}
+
+static u32
+cp2615_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm cp2615_i2c_algo = {
+	.master_xfer	= cp2615_i2c_master_xfer,
+	.functionality	= cp2615_i2c_func,
+};
+
+/*
+ * This chip has some limitations: one is that the USB endpoint
+ * can only receive 64 bytes/transfer, that leaves 54 bytes for
+ * the I2C transfer. On top of that, EITHER read_len OR write_len
+ * may be zero, but not both. If both are non-zero, the adapter
+ * issues a write followed by a read. And the chip does not
+ * support repeated START between the write and read phases.
+ */
+static struct i2c_adapter_quirks cp2615_i2c_quirks = {
+	.max_write_len = MAX_I2C_SIZE,
+	.max_read_len = MAX_I2C_SIZE,
+	.flags = I2C_AQ_COMB_WRITE_THEN_READ | I2C_AQ_NO_ZERO_LEN | I2C_AQ_NO_REP_START,
+	.max_comb_1st_msg_len = MAX_I2C_SIZE,
+	.max_comb_2nd_msg_len = MAX_I2C_SIZE
+};
+
+static void
+cp2615_i2c_remove(struct usb_interface *usbif)
+{
+	struct i2c_adapter *adap = usb_get_intfdata(usbif);
+
+	usb_set_intfdata(usbif, NULL);
+	i2c_del_adapter(adap);
+}
+
+static int
+cp2615_i2c_probe(struct usb_interface *usbif, const struct usb_device_id *id)
+{
+	int ret = 0;
+	struct i2c_adapter *adap;
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+
+	ret = usb_set_interface(usbdev, IOP_IFN, IOP_ALTSETTING);
+	if (ret)
+		return ret;
+
+	ret = cp2615_check_iop(usbif);
+	if (ret)
+		return ret;
+
+	adap = devm_kzalloc(&usbif->dev, sizeof(struct i2c_adapter), GFP_KERNEL);
+	if (!adap)
+		return -ENOMEM;
+
+	strncpy(adap->name, usbdev->serial, sizeof(adap->name) - 1);
+	adap->owner = THIS_MODULE;
+	adap->dev.parent = &usbif->dev;
+	adap->dev.of_node = usbif->dev.of_node;
+	adap->timeout = HZ;
+	adap->algo = &cp2615_i2c_algo;
+	adap->quirks = &cp2615_i2c_quirks;
+	adap->algo_data = usbif;
+
+	ret = i2c_add_adapter(adap);
+	if (ret)
+		return ret;
+
+	usb_set_intfdata(usbif, adap);
+	return 0;
+}
+
+static const struct usb_device_id id_table[] = {
+	{ USB_DEVICE_INTERFACE_NUMBER(CP2615_VID, CP2615_PID, IOP_IFN) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, id_table);
+
+static struct usb_driver cp2615_i2c_driver = {
+	.name = "i2c-cp2615",
+	.probe = cp2615_i2c_probe,
+	.disconnect = cp2615_i2c_remove,
+	.id_table = id_table,
+};
+
+module_usb_driver(cp2615_i2c_driver);
+
+MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
+MODULE_DESCRIPTION("CP2615 I2C bus driver");
+MODULE_LICENSE("GPL");